Microflora populations containing disproportionate concentrations of undesirable organisms can be treated with antibiotics or cleansing regimes to eliminate most of the organisms in the gut, both desirable and undesirable, followed by probiotic supplement to reestablish microflora balance. High doses of probiotics, consumed in the form of fermented foods containing the active probiotic organism or as nutritional supplements containing a specific minimum colony count of the probiotic are somewhat effective in controlling undesirable organisms. To be effective, large doses of the probiotic must be taken regularly to establish and to maintain colonization and to overcome the adverse environment created by undesirable organisms (Handbook of Prebiotics and Probiotics Ingredients, CRC Press, Boca Raton, Fla. 2009).
To assist in establishing probiotic colonization in the presence of large established populations of undesirable organisms, prebiotics, which are usually non-digestible carbohydrates can be used. These carbohydrate are selected for their ability to feed the probiotic organism preferentially and/or inhibit the growth or the undesirable organism. Id.
Another mechanism which has been described for prebiotic function is inhibition of adhesion by undesirable microorganism to the intestinal wall (Quintero, M. I., “Adherence Inhibition of Cronobacter Sakazakii and Other Pathogens By Prebiotic Oligosaccharides, Plant Extracts, and Other Naturally Derived Molecules,” Dissertations & Theses in Food Science and Technology, University of Nebraska, Lincoln, Apr. 22, 2011). When adverse organisms are able to adhere and establish colonization, they modify the local environment to enhance its survival and to inhibit the colonization by competing with desirable organisms. Certain non-fermentable carbohydrates have structures resembling those found in the surface of epithelial cells. These prebiotics bind to the undesirable bacteria preventing it from adhering to the intestinal wall and allowing the organism to pass out of the digestive tract. Of course once the organism is attached to the intestinal wall, the prebiotic may be ineffective in dislodging it.
The major products of probiotic metabolism are short chain fatty acids (SCFAs), the gases hydrogen and carbon dioxide, and bacterial cell mass. Unwanted symptoms relating to gas production in the gut are widely reported in human prebiotic feeding studies including flatulence, bloating and diarrhea. Increased cell mass and unutilized prebiotic carbohydrate can produce an undesired laxative effect by stimulation of peristalsis due to the increased bowel content (Gibson, G. R., et al., “Selective Stimulation of Bifidobacteria in the Human Colon by Oligofructose and Inulin,” Gastroenter 108:975-982, 1995).
In addition to polysaccharides, certain proteins and peptides and lipids also improve the growth of probiotics by inhibiting the undesirable organisms. Examples are lactoferrin, proanthocyanidins, and a high molecular weight component of cranberry juice. These materials may have several mechanisms which inhibit colonization by undesirable organisms including inhibition of adherence. (Ofek I., et al., “Anti-adhesion Therapy of Bacterial Diseases,” FEMS Immunol Med Microbiol 38:181-191, 2003.) These materials are quite expensive and require high concentrations to be effective and their specificity may be more broad spectrum antibiotic than desired.
What are needed are new compositions for increasing the growth of desirable microflora. The methods and compositions disclosed herein accomplish this goal by administering one or more bacteriophage, which lyse specific harmful and undesirable bacteria thus decreasing specific bacterial populations and thereby adding nutrients to the environment for the desirable bacteria.